Tuesday, September 26, 2017

Ancient Lake On Mars Was Hospitable Enough To Support Life

An illustration showing how the lake in the crater might have looked.

Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS
An up-close view of Mars' rocky deposits by NASA's Curiosity rover
shows a changing climate in the planet's ancient past that would have
left the surface warm and humid enough to support liquid water — and
possibly life. Evidence of an ancient lake points to the prospect of two
unique habitats within its shores; the lower part of the lake was
devoid of oxygen compared to an oxygen-rich upper half.

In a recent paper published in the journal Science, Redox
stratification of an ancient lake in Gale crater,” Stony Brook
University geoscientist Joel Hurowitz and his colleagues used more than
three years of data retrieved from the rover to paint a picture of
ancient conditions at Gale Crater,
the lowest point in a thousand kilometers. The site, a 150-mile
kilometer crater formed during an impact around 3.8 billion years ago,
once flowed with rivers ending in a lake. The sedimentary rocks laid
down by these rivers and onto the lakebed tell the story of how the
environment changed over time.
Curiosity landed on a group of sedimentary rocks known as the Bradbury
group. The rover sampled a part of this group called the Sheepbed
mudstones, as well as rocks from the Murray formation at the base of the
5-kilometer high peak at the center of the crater known as Mount Sharp.
Both types of rocks were deposited in the ancient lake, but the
Sheepbed rocks are older and occur lower in the stratigraphic layers of
rocks. Comparing the two types of rocks can lead to interesting
revelations about the paleoenvironment. [Life on Mars: Exploration & Evidence]